The system uses a handful of old, discarded smartphones which hide in a forest and generate a text message to alert reserve managers about poachers and illegal loggers.

Each smartphone is tricked out with a solar charger and reprogrammed to conduct audio surveillance.

The smartphones, encased in waterproof housings and attached to a cluster of solar cells, look like large, black flowers, 'Scientific American' reported.

They are mounted high in the canopy, where they are hard to spot. The devices periodically record snippets of audio, which they transmit over the cheap local cellular network to a central server.

If the software detects the sound of chain saws, it triangulates the position of the logging and sends the information to workers at the preserve.

The smartphones were installed into the forest canopy of the Kalaweit Supayang Nature Conservation Reserve for gibbons in Indonesia, where the system quickly brought logging to a halt, said Topher White, who designed the system and founded the company.

White said within 24 hours of activating four strategically positioned bugs in the reserve, the devices picked up illegal loggers and dispatched authorities.

After two weeks of operation, loggers stopped entering the 135-hectare region covered by the system. A year on, they have not returned, he said.

The start-up is now preparing to deploy dozens of such listening devices in equatorial Africa to protect endangered forest elephants and their habitats.